Older adults report problems in performing activities involving visual search, even when they are in good eye health. Research has indicated that visual search consists of two stages, a fast parallel stage that can process basic visual information across the visual field, and a slow serial stage that processes more complex information over a limited part of the field at one time. Studies have shown that older adults' visual searches take longer and are more vulnerable to distractors. However, there is disagreement in the aging literature about whether or not age- differences in visual search are found at the serial level only or at both the serial and parallel levels. It could be that older adults' deficits in parallel processing are more readily revealed when searching for targets over a large area of visual field. Furthermore, their deficit may partly stem from a problem with spatially localizing objects. These hypotheses will be examined using visual search tasks from the literature which have proven to be so useful in understanding the mechanisms underlying human- visual search performance. The major questions to be addressed are: a) How does aging affect parallel search over small display areas and is this search unaffected by set size as it is in younger adults?; b) Is the disagreement in the literature due to early studies confining stimulus displays to small visual field areas? That is, perhaps older adults reveal parallel processing deficits when they are required to process information over large field areas; c) Could older adults' problems in visual search be attributed to a spatial localization problem?; d) How is the parallel system being used to guide visual search in older adults? The project will utilize standard visual search tasks (feature and conjunction search) as tasks as tools to help resolve some of the discrepancies in the aging and visual search literature. The results of these experiments will contribute to a better understanding of what mechanisms underlie older adults' problems in locating objects of interest in the environment.